Strict budget, slow restoration. *Now with moar budget*

[Wh33lhop]

So now the G250 and the 3.23 diff are in, but the diff doesn't want to lock. It feels tired. So, out it comes.

My patented double-screwdriver method of cap removal. Much more effective pulling from both sides at once than going around and prying slowly with just one screwdriver.


I also gutted my 3- clutch 4.10 in case I needed parts. Messy oprtation.


Here's what I found inside the 3.23. A factory 4 clutch diff! Pretty cool, haven't seen one before.




The clutches don't look worn at all, plus they measure out to 2.0mm apiece.


Hard to tell from the pic but the 4 clutch top cap (on the right) is 1.5mm thinner than the 2 clutch top cap (left), to make some extra room:


Here's my shitty diff guts diagram.


So, if the clutches are in good shape, why isn't it locking? I notice two differences between this diff and the 3 clutch I built.
1. Belleville washers. These are basically circular springs inside the diff that provide preload. The 4 clutch 3.23 didn't have any in it, which will mean there's no preload.
2. The ramps. The ramps in the 4 clutch are asymmetric but are also quite tame, looking like 60 degrees or more.

Here are the normal 45 degree ramps in the 3 clutch that locks well:


And here are the grandma ramps in the 4 clutch that won't lock:


The weaker ramps are also asymmetric which means they could have been installed backwards making lockup even weaker.

So, I put the more aggressive 45 degree ramps in and replaced the 2.4mm spacer with a Belleville washer in the 4 clutch diff and put it back in. It locks fantastically now, but has a bit too much preload for my liking. I may take it out later to remove some of that preload as it makes the car push mid corner.

[Wh33lhop]

Next, time for a track day. I have always left everything in the car for events including the spare and sub, but now I am starting to care about laptimes so I removed about 140lbs worth of stuff including the 65lb lukebox/amp and spare.



(Re)installing racecar stuff!


After taking some weight out I was able to manage a 5.7 0-60, not exactly fast but not bad considering you need 2 shifts.


I'd like to do a full 1/4 mile run but that's a little tougher to do on the street.

And a nice treat a friend had lying around that I got super cheap: an M3 cluster. You need an E28 M5 coding plug to make it work with a 6 cylinder motor, which is about $45 shipped.


Unfortunately you have to cut away the housing of your brand new coding plug as it won't fit in the E30 cluster. Just use the board.

Here's the final product. I don't really care about the M badging but it does add a nice touch to the car.

[Wh33lhop]

Oh yeah, managed a bunch of low 1:45s at Laguna. So close to a 1:44 but I couldn't string it together when there was no traffic. :(



(sorry for vid quality)

[Reichart12]

That 0-60 tracker is pretty cool, what model is it?

[Wh33lhop]

It's an AiM Solo! 0-60 is just a simple feature, it's a full datalogger that's extremely useful on track--it's also the reason I have telemetry on my track videos.

[tinkerputzer]

I love this thread for it's function over form nature.

Only car i know that had 4 clutch unsprung lsd's was a handful of z3m's. Never seen one though. Thanks for posting pics of it. I've heard running unsprung set ups require a lot of maintenance and are quite touchy so it's no surprise it's got mild ramps.

I think the way you set it up with one belville was a good choice but you should try it with the asymmetric ramps. Or if that isn't to your liking have some 30* accel ramps machined. The 45* ramps on the decel side is always going to cause a bit of understeer.

A little OT but where can i find the best deal on lasagna pans? You always seem to have a surplus :)

[Wh33lhop]

Thank you sir!

I'd love to machine some ramps but that is not cost effective--ramps are not cheap and so far I have $0 into this diff. :p The clutch pack/steels in the 3 clutch are all 3.5mm stacked instead of the standard 4.0 in the 4 clutch so I will probably swap one or two out to alleviate some preload. If I like it then I'll put the 3 clutch 4.10 back together with the remainder of the parts and the asymmetric ramps (hopefully I'll install them in the correct orientation!) and slap it in the auto black 2dr to see if it's any good like that.

Ha! I get em at the Smart and Final down the street whenever I have messy work; the big ones are like a dollar and the smaller ones are $0.69. :)

[phreshkid]

great, now I want lasagna at the track in between laps.

[agent]

0:30 :mrgreen:

Time for a cage, brah.

[tinkerputzer]

I'd love to machine some ramps but that is not cost effective--ramps are not cheap and so far I have $0 into this diff. :p The clutch pack/steels in the 3 clutch are all 3.5mm stacked instead of the standard 4.0 in the 4 clutch so I will probably swap one or two out to alleviate some preload. If I like it then I'll put the 3 clutch 4.10 back together with the remainder of the parts and the asymmetric ramps (hopefully I'll install them in the correct orientation!) and slap it in the auto black 2dr to see if it's any good like that.

True getting ramps machined is somewhat pricey but for what you are doing it would make a world of difference. Diffsonline was the most reasonable when i had mine done.

To avoid sounding like i'm questioning your every move i'd like to add a disclaimer. **I enjoy discussing LSD set up with anybody willing to discuss LSD setup since most people who set up LSD's don't like to share info.** Phew let's get started :)

I'm looking at your diff guts diagram above and i calculate a total installed clearance of .9mm. IIRC bmw recommends .1-.3mm total installed clearance. What did you end up with for break away torque and what kind of fluid were you using to while assembling? I ask because I don't see how you could end up with too much static preload with that kind of installed gap, therefor i don't think adding more gap will solve you're understeer issue. I still think that's being caused by the 45* decel ramps.

FWIW when i set up my 4 clutch unit with 30/90 ramps i ended up with .3mm. I think that gave me around 80 ft/lb break away torque, but that was checked with non slip fluid so now that i'm running friction modifiers it's probably a bit lower.

Going back to that unsprung LSD were the dimensions the same, as your diagram, aside from the bellville on the bottom? Did they have a spacer on the bottom? If so how thick? I've always wondered how bmw set that LSD up from the factory. I'm not sure but i think running an unsprung LSD like that would be best with non slip fluid.

I'd be curious to see how the ramps from that unsprung LSD would react to preload. Might not be enough accel lock but decel should be nice.

Oh yeah when installing asymmetrical ramped pressure rings the accel ramps should point down as assembled in the diff from a aft looking fwd pov. So it should look kind of like an upside down teardrop.

Ha! I get em at the Smart and Final down the street whenever I have messy work; the big ones are like a dollar and the smaller ones are $0.69. :)

Great now every time i'm at smart and final i'll be checking prices on lasagna trays :)

Got a chance to watch your 1:45's at Laguna Seca. That's hauling ass for that car! I recently got a ride along around laguna seca in a k24 swapped miata and he was running 1:46's. I thought that was hauling. So i gotta hand it to you for the times your turning in the whee30 :up:

[Wh33lhop]

great, now I want lasagna at the track in between laps.

I want lasagna always.

0:30 :mrgreen:

Time for a cage, brah.

I know! There was a fatality at Buttonwillow (RIP :() the weekend prior to me going out, car even had a full cage but no HANS. I think a half cage, HANS and harnesses is next on the mod list but I'm not sure when it'll happen... sadly it all comes down to money and thats a pretty big hit, no pun intended.

True getting ramps machined is somewhat pricey but for what you are doing it would make a world of difference. Diffsonline was the most reasonable when i had mine done.

To avoid sounding like i'm questioning your every move i'd like to add a disclaimer. **I enjoy discussing LSD set up with anybody willing to discuss LSD setup since most people who set up LSD's don't like to share info.** Phew let's get started :)

I'm looking at your diff guts diagram above and i calculate a total installed clearance of .9mm. IIRC bmw recommends .1-.3mm total installed clearance. What did you end up with for break away torque and what kind of fluid were you using to while assembling? I ask because I don't see how you could end up with too much static preload with that kind of installed gap, therefor i don't think adding more gap will solve you're understeer issue. I still think that's being caused by the 45* decel ramps.

FWIW when i set up my 4 clutch unit with 30/90 ramps i ended up with .3mm. I think that gave me around 80 ft/lb break away torque, but that was checked with non slip fluid so now that i'm running friction modifiers it's probably a bit lower.

Going back to that unsprung LSD were the dimensions the same, as your diagram, aside from the bellville on the bottom? Did they have a spacer on the bottom? If so how thick? I've always wondered how bmw set that LSD up from the factory. I'm not sure but i think running an unsprung LSD like that would be best with non slip fluid.

I'd be curious to see how the ramps from that unsprung LSD would react to preload. Might not be enough accel lock but decel should be nice.

Oh yeah when installing asymmetrical ramped pressure rings the accel ramps should point down as assembled in the diff from a aft looking fwd pov. So it should look kind of like an upside down teardrop.

That diagram was actually before I changed anything. :p The bottom was a ~2.4mm spacer and that's how much slack it came with, but keep in mind it may have been gone through prior... PO pulled it out and had a rebuilt diff installed so for all I know he may have used it as a parts diff or something. Bellevilles are ~4.6mm tall but ~2.5mm thick so in theory they can be anything in between those... There was 3.3mm worth of slack after removing the spacer, so I just slapped a belleville in there which compresses it thereabouts 1.3mm. IIRC there was about 1mm total compression in the bellevilles in the other diff so this would be a bit more preload force plus an extra clutch. It's not just the mid corner push you notice, you can even feel the preload driving down the street--the steering will center itself because of the diff.

I also did not check breakaway torque, just put in car and prayed. :) Redline 75W140 LS from the get-go!

Great now every time i'm at smart and final i'll be checking prices on lasagna trays :)

Got a chance to watch your 1:45's at Laguna Seca. That's hauling ass for that car! I recently got a ride along around laguna seca in a k24 swapped miata and he was running 1:46's. I thought that was hauling. So i gotta hand it to you for the times your turning in the whee30 :up:

Thank you sir! It's still got another second in it! :p I think if I am more consistent and try and use reference points everywhere instead of drive by the seat of my pants I can do better... I just forget all that as soon as I get on track.

[agent]

I think a half cage, HANS and harnesses is next on the mod list but I'm not sure when it'll happen... sadly it all comes down to money and thats a pretty big hit, no pun intended.

I definitely feel ya. I have a HANS already but the rest of those items are on Lola's list too, along with fixed backs.

I've been promoted to A-solo, though I promised myself I wasn't going to run in that group until I got those things done.

[kronus]

get a nexgen, they are a fair bit cheaper than a HANS but do the same thing. (it's what most of us run in cheesy)

[tinkerputzer]

That diagram was actually before I changed anything. :p The bottom was a ~2.4mm spacer and that's how much slack it came with, but keep in mind it may have been gone through prior... PO pulled it out and had a rebuilt diff installed so for all I know he may have used it as a parts diff or something. Bellevilles are ~4.6mm tall but ~2.5mm thick so in theory they can be anything in between those... There was 3.3mm worth of slack after removing the spacer, so I just slapped a belleville in there which compresses it thereabouts 1.3mm. IIRC there was about 1mm total compression in the bellevilles in the other diff so this would be a bit more preload force plus an extra clutch. It's not just the mid corner push you notice, you can even feel the preload driving down the street--the steering will center itself because of the diff.

I also did not check breakaway torque, just put in car and prayed. :) Redline 75W140 LS from the get-go!

Ah ok, so that would still leave you with around .8mm clearance though. Interesting that it's still plowing like a bulldozer, but that is the nature of a LSD with bellvilles. I wish i could be more helpful but i'm kind of out of ideas. I'll be interested in what you come up with as a solution.

FWIW other cars that run unsprung ZF LSD's have around .5-.8mm installed clearance so that Z3 LSD wasn't too far gone. Any more clearance than that and the ramps with take a beating. I'd think running it with out friction modifiers and more aggressive accel ramp angles would be the way to go though.

[Wh33lhop]

No, there is no slack with the Belleville.

Bellevilles, fully uncompressed are ~4.6mm thick when in the stack. I measured the thickness of the material to be about 2.5mm and therefore surmised that they could be compressed down to 2.5mm. So with Bellevilles there is no "slop" in the stack at all--the Belleville should be taking up all of the clearance, otherwise it is just acting as a 4.6mm spacer.

Ramps would be great but again, totally cost prohibitive. I'll put that $450 towards safety and that is a no-brainer for me.